Shijimi (Japanese Freshwater Clam)

Shijimi is the Japanese freshwater clam Corbicula japonica, harvested from Japan's brackish lakes and lower river systems. The clams are small (1-2cm shell length), with characteristic dark shells, and live primarily in brackish (slightly saline) environments. Production is concentrated in Lake Shinji (Shimane Prefecture, the largest source — accounting for ~40% of Japanese supply), Lake Ogawara (Aomori), and the Tone River system (Ibaraki).

Shijimi's nutritional distinction is its ornithine content (~10-15 mg per 100g) — among the highest of any commonly consumed food. Combined with rich vitamin B12 (44.8 μg per 100g — exceptionally high), iron (8.3 mg per 100g), and taurine, shijimi has been positioned around liver health, urea cycle support, and recovery from alcohol consumption since ancient Japanese folk tradition.

Industrially, shijimi is supplied as: (a) live and frozen whole clams for foodservice and retail, (b) concentrated shijimi extract (the active ingredient for supplements), (c) freeze-dried shijimi for instant soup and supplement applications, (d) shijimi-extract supplements (capsule, granule, drink format), and (e) ready-to-eat shijimi miso soup products (retort, freeze-dried, bottled). Premium product positioning often names Lake Shinji ('Yamato Shijimi') or other origin lakes for authenticity claims.

Shijimi miso soup (しじみ味噌汁) — the most established traditional Japanese application. Whole shijimi clams cooked in dashi and miso produce a deeply umami broth with the clams as edible garnish. Iconic Japanese washoku dish associated with morning meals and post-drinking recovery.

Shijimi extract supplements — Japan's largest ornithine-positioning supplement category. Liquid drinks, capsules, and granular supplements positioned for liver health, fatigue recovery, and post-drinking wellness. Major brands (Yawata, DHC, Asahi) all have established shijimi-extract product lines.

Hangover-recovery beverages — concentrated shijimi extract is the principal active ingredient in Japan's distinctive 'hangover prevention/recovery' beverage category. Major convenience store and pharmacy retail.

Premium ready-meals and instant soup — freeze-dried shijimi miso soup, retort shijimi soup, and frozen shijimi-based products are established premium ready-meal categories.

FFC (Foods with Function Claims) products — shijimi-extract supplements with documented evidence for liver function support or fatigue-recovery claims under FFC notification.

For OEM: shijimi extract supply for supplement and beverage formulators, freeze-dried shijimi for instant soup and supplement applications, premium retort shijimi miso soup products, and concentrated shijimi extract for hangover-recovery beverage and supplement formulations.

As food: shijimi follows standard shellfish labeling.

As supplement: ornithine claims require FFC notification with documented evidence of efficacy. Some products have made FFC notifications for liver function support.

Premium origin claims (Lake Shinji 'Yamato Shijimi', Lake Ogawara) require verifiable supply chain documentation.

Allergens: shijimi is shellfish — clam allergen disclosure is required.